Multiple-station selective communication system with single amplifier



MULTIPLE-STATION SELECTIVE COMMUNICATION SYSTEM WITH SINGLE AMPLIFIERFiled March 19, 1953 Aug- 28, 1956 E J. NovREsKE 2,761,014

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FOU/Q MULTIPLE-STATION SELECTIVE COMMUNICA- TION SYSTEM WITH SINGLEAMPLIFIER Emanual J. Novreske, Gary, Ind., assigner to United StatesSteel Corporation, a corporation of New Jersey Application March 19,1953, Serial No. 343,428

2 Claims. (Cl. 179-40) This invention relates to an improved multiplestation selective communication system.

An object of the invention is to provide a system of the foregoing typewhich includes as many stations as desired and in which any station cancommunicate both ways with any other station with only a singleamplifier for the entire system.

A further object is to simplify communicating systems of the foregoingtype by employing only a single amplifier for the entire system whileallowing two-way communication between any two stations thereof.

In accomplishing these and other objects of the invention, I haveprovided improved details of structure, a preferred form of which isshown in the accompanying drawing, in which:

The single figure is a schematic wiring diagram of a communicationsystem embodying the present invention.

The communication system of my invention comprises any desired number ofstations, illustrated as four in number, and designated in the drawingby the legends Station One, Station Two, etc. Each station includes acombination speaker and microphone 10, a press-to-talk key 12, and threestation selector switches 13 which are designated by appropriatelegends. These selector switches normally are open. When a user at anystation talks to another station, he closes the selector switch at theformer station indicated by the legend thereon as connected to thelatter station. The system also comprises a single amplifier and powersupply unit 14. Inasmuch as the combination speakers and microphones andthe amplifier and power supply unit per se can be of any standard ordesirable construction and are not part of the present invention, nodetailed showing is included.

Each press-to-talk key 12 has three front or normally open contacts 15,16 and 17 and two back or normally closed contacts 18 and 19. This keynormally is in a position for its station to receive communications fromthe other stations and thus for the combination speaker and microphone10 to function as a speaker. Conductors 20 and 21 connect thecombination speaker and microphone lil with the back contacts 18 and 19respectively as long as the key is in its normal receiving position. Theback contact 18 of the key in Station One is connected to one of fourconductors 22. This conductor 22 has branches which extend to thestation selector switch for Station One in each of the other stations.The back contacts 18 of the keys in the other stations arecorrespondingly connected to similarly arranged conductors 22 so that,whenever a station selector switch in any of the stations is closed, aconnection is established from that switch to the back contact 18 of theselected station. The back contacts 19 of the keys of all the stationsare connected via a conductor 23 to one side of the output from theamplifier and power supply 14. The front contacts 17 of each key areconnected via a conductor 24 to each of the three selector switches 13of that station and via a conductor 25 to the other side of the StatesPatent VO ICC output from the amplier and power supply 14. Conductors 26and 27 connect the front contacts 15 and 16 respectively of each key 12to the input to said amplifier and power transformer.

In operation, assume as an example that a user at Station One wishes tocommunicate with another user at Station Four. The user at Station Onecloses both the Station Four selector switch 13 and the press-totalk key12, as indicated in dotted lines in the drawing. At Station One thecombination speaker and microphone 10 now acts as a microphone, and atStation Four as a speaker. At Station One conductors 20 and 21 areconnected through the key 12 to the front contacts 15 and 16 thereof(now closed), and said contacts are connected via the conductors 26 and27 to the input of the amplifier and power supply 14. Thus the spokensignal is transmitted to the amplifier. The conductor 23 connects oneside of the amplier output to the back contact 19 of the key 12 atStation Four. As long as said key is in its receiving position, theconductor 21 at this station connects this back contact with one side ofits speaker 10. At Station One the conductor 25 connects the other sideof the amplifier output to the conductor 24 via the front contacts 17(now closed). Also at Station One the selector switch for Station Four(now closed) connects the conductor 24 to the conductor 22 which leadsto the back contact 18 of Station Four. At the latter station theconductor 20 connects this contact with the other side of the speaker10. Thus there is established a complete circuit from the microphone ofStationOne through the amplifier and power supply 14 to the speaker ofStation Four. In like manner circuits can be set up from the microphoneof any of the stations through the amplifier and power supply to thespeaker of any other station by closing the appropriate key 12 andstation selector switch 13.

It is seen that the system of my invention enables a single amplifierand power supply to serve for the whole system. In usual installationswhen two-way communication is possible between all stations, separateamplifiers are required for each station.

While I have shown and described only a single embodiment of theinvention, it is apparent that modifications may arise. Therefore, I donot wish to be limited to the disclosure set forth but only by the scopeof the appended claims.

I claim:

1. A communication system comprising a single amplifier and powersupply, a plurality of stations, each of which includes a combinationspeaker and microphone, a press-to-talk key having two back and threefront contacts, connections between said back contacts and said speakerand microphone, and normally open station selector switches for theother stations arranged for connection to one of said front contactswhen the key is pressed, connections between each of said selectorswitches and one of the back contacts of the station to which itcorresponds, a connection between the output of said amplifier and powersupply and the other back contact of each station, a connection betweenthe output of said amplifier and power supply and that front contact ateach station arranged for connection to said station selector switches,and connections between the two other front contacts at each station andthe input to said amplifier and power supply, said last namedconnections being independent of the connections from the output of saidamplifier and power supply, said connections enabling any of saidstations to communicate both ways with 'any other with only oneamplifier.

2. A communication system comprising a single amplifier and power supplyhaving a pair of input terminals and a pair of output terminals, aplurality of stations each having a combination speaker and microphone,a press-to-talk keynormally in a receiving position, and normally openstation selector switches for the other stations, each of saidcombination speakers and microphones having connections with one of saidoutput terminals and with the selector switches therefor at the otherstations via its own key when lthe latter is in its receiving position,conductors between the other output terminal and said keys and betweeneach of said keys and the selector switches at that station, saidconductors completing a circuit from said other output terminal to oneof said combination speakers and microphones when the key at any otherstation is in its transmitting position and the corresponding selectorswitch at that other station is closed, and conductors between each ofsaid keys and both of said input terminals, said last named ReferencesCited in the le of this patent UNITED STATES PATENTS 2,275,405 BerhleyMar. 10, 1942 2,493,174 Vincent Ian. 3, 1950 2,523,671 Vincent Sept. 26,1950 2,554,912 Kilminster May 29, 1951 2,561,946 Pedatella July 24, 1951

